Li Kaixia, Zhang Xubo, Zuo Ying, Liu Weimin, Zhang Jianzhen, Moussian Bernard
Research Institute of Applied Biology, Shanxi University, Taiyuan, 030006, China; College of Life Science, Shanxi University, Taiyuan, 030006, China.
Research Institute of Applied Biology, Shanxi University, Taiyuan, 030006, China.
Insect Biochem Mol Biol. 2017 Oct;89:1-10. doi: 10.1016/j.ibmb.2017.08.003. Epub 2017 Aug 15.
The insect cuticle is an extracellular matrix that consists of the polysaccharide chitin, proteins, lipids and organic molecules that are arranged in distinct horizontal layers. In Drosophila melanogaster, these layers are not formed sequentially, but, at least partially, at the same time. Timing of the underlying molecular mechanisms is conceivably crucial for cuticle formation. To study this issue, we determined the time period during which the function of Knickkopf (Knk), a key factor of chitin organization, is required for wing cuticle differentiation in D. melanogaster. Although knk is expressed throughout metamorphosis, we demonstrate that its expression 30 h prior and 48 h after pupariation is essential for correct wing cuticle formation. In other words, expression beyond this period is futile. Importantly, manipulation of Knk expression during this time causes wing bending suggesting an effect of Knk amounts on the physical properties of the wing cuticle. Manipulation of Knk expression also interferes with the structure and function of the cuticle surface. First, we show that the shape of surface nano-structures depends on the expression levels of knk. Second, we find that cuticle impermeability is compromised in wings with reduced knk expression. In summary, despite the extended supply of Knk during metamorphosis, controlled amounts of Knk are important for correct wing cuticle differentiation and function in a concise period of time.
昆虫角质层是一种细胞外基质，由多糖几丁质、蛋白质、脂质和有机分子组成，这些成分排列成不同的水平层。在黑腹果蝇中，这些层不是依次形成的，而是至少部分地同时形成。潜在分子机制的时间安排对于角质层形成可能至关重要。为了研究这个问题，我们确定了几丁质组织的关键因子Knickkopf（Knk）的功能在黑腹果蝇翅角质层分化过程中所需的时间段。尽管knk在整个变态过程中都有表达，但我们证明其在化蛹前30小时和化蛹后48小时的表达对于正确的翅角质层形成至关重要。换句话说，超出这个时间段的表达是无效的。重要的是，在此期间操纵Knk的表达会导致翅弯曲，这表明Knk的量对翅角质层的物理性质有影响。操纵Knk的表达也会干扰角质层表面的结构和功能。首先，我们表明表面纳米结构的形状取决于knk的表达水平。其次，我们发现knk表达降低的翅中角质层的不透性受损。总之，尽管在变态过程中Knk的供应时间延长，但在一段特定的时间内，适量的Knk对于正确的翅角质层分化和功能很重要。
